This invention relates to a pipe handling apparatus for oil drilling operations and earth drilling operations, and more particularly to a pipe handling apparatus which is capable of mechanically carrying out the transportation of short pipes between a pipe storage rack and the oil well center, pipe lifting and lowering operations and the storage and transportation of stand pipes, and thereby improving the safety of a pipe handling operation and the oil productivity.
To drill a submarine oil well, a floating or seafloor-set marine structure is generally used. On this marine structure, a tower is set up as the equipment for lifting and lowering drill pipes for boring the seafloor and casing pipes to be inserted as the reinforcing materials into a borehole. The drill pipes in an oil well are piled up generally in a place (pipe storage space) which is apart from the tower. Every time an oil digging operation is started, the drill pipes are transferred from the pipe storage space to the interior of the tower.
To insert a drill pipe into the well center or a mousehole provided in the tower, it is necessary that the drill pipe be suspended vertically. To meet this requirement in a conventional apparatus of this kind, a drill pipe is suspended at one end portion thereof from a suspension means such as a crane and carried from a pipe storage space to the interior of the tower. However, when a drill pipe is transported as it is suspended at one end portion thereof, the pipe is shaken by waves and wind. Consequently, the drill pipe may strike the tower or fall, causing a major accident. To prevent such an accident, much labor is required to hold the pipe firmly, so that the oil drilling operation cannot be carried out in the desired manner.
There is a known apparatus shown in FIGS. 8 and 9, which is designed to carry out pipe lifting and lowering operations speedily and easily. Referring to the drawings, reference numeral 1 denotes guide rails set up on a floor surface within a floating oil drilling tower; and 3 and 4, carriages supported on the guide rails 1 so that the carriages can be moved up and down therealong. A suspension member 6 for a drill pipe 5 is provided on the lower carriage 4 via a parallel link 7 and a driving cylinder 8 so that the suspension member can be moved freely in the horizontal direction. An elevator hand 9 for clamping an upper end portion of the drill pipe 5 during a pipe lifting and lowering operation, or a lathe dog 10 for applying the rotary force to the drill pipe 5 during an oil drilling operation is attached exchangeably to the suspension member 6.
A main frame 12 having a heaving compensator (displacement-absorbing member) 11, which is adapted to suspend the suspension member 6 while absorbing the vertical displacement thereof, is provided on the upper carriage 3 via a parallel link 13 and a driving cylinder 14 so that the main frame 12 can be moved freely in the horizontal direction in a manner similar to the suspension member 6. This main frame 12 is suspended from a suspension cable 15, which is extended thereto from above, such that the main frame can be moved up and down. In a left unit thus constructed, the suspension member 6 and main frame 12 can be displaced in the horizontal direction. Accordingly, even when the drill pipe 5 is positioned in the well center or on the axis of a well 16, the suspension member 6 can be moved up and down without interfering therewith. This enables the pipe lifting or lowering operation to be carried out speedily and easily, and the pipe lifting and lowering cycle time to be reduced.
However, in this conventional apparatus, the suspension member 6 and main frame 12 are provided independently on two carriages 4 and 3, respectively, so that the suspension member 6 and main frame 12 must be moved synchronously in the horizontal direction. Therefore, it is difficult to operate the suspension member 6 and main frame 12. There is the possibility that these parts are operated erroneously to cause them to interfere with each other. Consequently, the ropes 17 in the heaving compensator 11 or a connecting means (not shown), by which the suspension member 6 and the main frame 12 are connected together, would be damaged during the pipe lifting and lowering operations.
A so-called pipe lifting operation is carried out in which a drill string inserted in a well being dug is withdrawn therefrom for the replacement of bits attached to the lowermost portions of the drill pipes. The drill string comprises bits, a plurality of drill collars connected to the bits and a great number of drill pipes connected to the upperemost portions of the drill collars. The drill string is divided into parts (so-called stand pipes) each of which has three connected drill pipes to constitute a unit object material in a pipe lifting operation. The stand pipes are stored in a standing state on the floor surface of the tower which is on the oil drilling rig. In the case of a 6000-meter class drill string, 220 pieces or so of stand pipes have to be housed in the tower. After a bit-replacing operation has been completed, these stand pipes are to be connected successively and lowered into the well. It is necessary, especially, on a marine rig that the stand pipes be supported so as to prevent them from falling due to the rolling of the rig. Therefore, the stand pipes must be stored within the tower reliably in good order. To meet these requirements, a pipe rack device shown in FIG. 10 has been provided. Referring to the drawing, reference numeral 18 denotes pipe storage grooves into which stand pipes 19 are slid diametrically so as to be housed therein. The plural pipe storage grooves 18 are formed in parallel with one another, and have entrances 20 on the same side thereof. Each of the pipe storage grooves 18 is provided therein with a plurality of flexible gates 21 which are spaced in the lengthwise direction of the groove 18 and adapted to support the stand pipes 19. The pipe storage grooves 18 are a groove for housing stand pipes 19' of drill collars, and grooves for housing stand pipes 19" of drill pipes.
There is a certain type of drill collar which is provided with a deviation-preventing stabilizer, and such a stabilizer-carrying drill collar is connected to a regular drill collar as the former is spaced suitably from the latter.
In the conventional pipe handling apparatus, the stand pipes 19' of drill collars are stored in the same pipe storage groove 18 as mentioned above. Accordingly, it is necessary that the stand pipes 19' be always taken out during a pipe lowering operation in the order which is opposite to the order in which the stand pipes 19' were stored. Hence, it is impossible to take out an arbitrary stand pipe selectively for the purpose of varying the arrangement of the stabilizer-carrying drill collars.
A stand pipe transfer unit is used as means for carrying a stand pipe from a rack to an oil well or vice versa during pipe lifting and lowering operations. This transfer unit comprises, generally, an upper hand for clamping an upper portion of a stand pipe and a lower hand for clamping a lower portion thereof.
However, in the conventional stand pipe tranfer unit, a lower hand 22 is formed so as to extend at right angles to the storage grooves 18 in a rack 23, and has a one-side-openable hand member 24 which opens on the side, as shown in FIG. 11. Therefore, the operation of the transfer unit is so limited that it necessarily transfers such stand pipes first that are housed in a front storage groove 18, and thereafter the stand pipes housed in a rear storage groove adjacent thereto. Moreover, since the stand pipe transfer unit must be rendered usable for transferring the stand pipes in the left and right racks 23 and 23', the hand member 24 must be changed from a rightward-openable hand member to a leftward-openable hand member or vice versa so as to prevent the hand member 24 from interfering with a stand pipe in a pipe storage groove. Hence, the pipe transfer unit cannot be operated easily.
The present invention was made with a view to eliminating the above-mentioned drawbacks encountered in the prior art pipe handling apparatus. An object of the present invention is to provide a pipe handling apparatus for oil drilling operations, which is capable of handling pipes speedily and easily with little labor, and improving the safety of pipe lifting and lowering operations and oil productivity.
According to the present invention, a short-pipe transfer unit for transferring a short pipe between a pipe storage space and an oil well center, a lift unit for vertically displacing the transferred short pipe, a stand-pipe rack unit for holding in a standing state a stand pipe consisting of a plurality of connected short pipes and withdrawn from the oil well and a stand-pipe transfer unit for transferring a stand pipe between the stand-pipe rack unit and the oil well center are improved, respectively, and combined unitarily and operatively so as to achieve the above-mentioned object. An apparatus according to the present invention comprises a short pipe transfer unit having guide rails extending from a pipe storage space, in which short pipes comprising drill pipes and drill collars are stored, to a position above the oil well center, and a carriage on said guide rails so as to transfer said short pipes; a pipe lift unit having a suspension member suspended from a cable via a displacement-absorbing member above said oil well center so that said suspension member can be moved vertically and horizontally, said pipe lift unit being adapted to lift and lower a short pipe from and into said oil well center; a stand pipe rack unit having a plurality of storage grooves for holding therein in a standing state stand pipes each of which has been withdrawn from said oil well center and comprises a plurality of short pipes, and storage chambers formed at entrance portions of said storage grooves and adapted to hold therein said stand pipes each of which comprises drill collars; and a stand pipe transfer unit having a post provided movably between said stand pipe rack unit and said oil well center, and hands on said post and adapted to clamp the upper and lower ends of said stand pipe.
A preferred embodiment of the present invention will now be described with reference to the accompanying drawings.